Infrared-Based Vehicle Component Imaging and Analysis

ABSTRACT

An improved system for evaluating one or more components of a vehicle is provided. The system includes a set of imaging devices configured to acquire image data based on infrared emissions of at least one vehicle component of the vehicle as it moves through a field of view of at least one of the set of imaging devices. An imaging device in the set of imaging devices can include a linear array of photoconductor infrared detectors and a thermoelectric cooler for maintaining an operating temperature of the linear array of detectors at a target operating temperature. The infrared emissions can be within at least one of: the mid-wavelength infrared (MWIR) radiation spectrum or the long wavelength infrared (LWIR) radiation spectrum.

REFERENCE TO RELATED APPLICATIONS

The current application is a continuation of U.S. patent applicationSer. No. 13/895,275, which was filed on 15 May 2013, and which claimsthe benefit of U.S. Provisional Application No. 61/688,843, titled“Infrared array for high speed diagnostic imaging,” which was filed on23 May 2012, both of which are hereby incorporated by reference.

TECHNICAL FIELD

The disclosure relates generally to wheeled vehicle monitoring, and moreparticularly, to a solution for evaluating a condition of a wheel,bearing, brake system, and/or the like, of a passing wheeled vehicle.

BACKGROUND ART

Effective detection of one or more flaws in vehicles, such as rollingstock components in the rail industry, or commercial trucks, is highlydesirable. For example, detection of flaws or problems with the wheels,brake components (including drums, discs, etc.), electronic brakecontrol systems, air conditioning units, transmission, driving motors,and/or the like, is desirable so that corrective action can be taken,e.g., to prevent a derailment, highway accident, further damage, fire,or the like.

Current detectors include detectors that attempt to detect bearingoverheating (e.g., hot box detectors) and detectors that attempt todetect brake/wheel component overheating (e.g., hot wheel detectors).The rail industry has utilized hotbox detectors for over fifty years todetect overheating bearings and thereby prevent derailment. Thesethermal detectors are mounted on the rail or in close proximity to therail to provide hot bearing and hot wheel data.

Measurements made with such single element detectors are subject tolarge errors due to variations in emissivity of bearing and wheelradiating surfaces. The infrared detectors typically used, such asthermoelectric, thermistor bolometer and pyroelectric detectors, alsousually are limited to monitoring lower speed vehicles, e.g., vehiclestypically traveling under one hundred fifty kilometers per hour.However, higher speed trains in use in Europe can travel as fast as fourhundred fifty kilometers per hour.

Currently used thermal detectors monitor radiation in the long waveinfrared (LWIR) region, e.g., having wavelengths between eight andfourteen microns. Thermal detectors are inherently slow as infraredabsorption is followed by heating of the detector element mass. Heatingof the detector element results in a physical property change, e.g.,resistance change for the thermistor bolometer. An additional issue withexisting rail mounted hot box detectors is microphonic noise generatedby the pyroelectric detections in response to rail shock and vibration.Other difficulties with the use of conventional hot box and hot wheeldetectors are the relative high cost of LWIR optics fabricated fromgermanium or special long wave infrared glasses, and the considerablemotion induced blurring conspicuous with vehicles moving at higheroperating speeds.

Previous approaches have proposed using arrays of pyroelectric detectorsand thermopiles for hot wheel and hot bearing detection. For example,one approach includes a hot wheel detector that utilizes an eightelement linear array of pyroelectric detectors. Another approach uses avacuum packed micro thermopile (thermoelectric) array for wheel andbearing monitoring. However, these array detectors suffer from many ofthe drawbacks listed above regarding the use of conventional bolometertype thermal detectors in the LWIR region for hot wheel and hot bearingdetection.

SUMMARY OF THE INVENTION

Aspects of the invention provide an improved system for evaluating oneor more components of a vehicle. The system includes a set of imagingdevices configured to acquire image data based on infrared emissions ofat least one vehicle component of the vehicle as it moves through afield of view of at least one of the set of imaging devices. An imagingdevice in the set of imaging devices can include a linear array ofphotoconductor infrared detectors and a thermoelectric cooler formaintaining an operating temperature of the linear array of detectors ata target operating temperature, e.g., below ambient, for improvedsensitivity. The infrared emissions can be within at least one of: themid-wavelength infrared (MWIR) radiation spectrum or the long wavelengthinfrared (LWIR) radiation spectrum.

A first aspect of the invention provides a system comprising: an imagingcomponent including a set of imaging devices configured to acquire imagedata based on infrared emissions of at least one vehicle component of avehicle moving through a field of view of at least one of the set ofimaging devices, wherein an imaging device in the set of imaging devicesincludes a lead selenide detector and a thermoelectric cooler formaintaining an operating temperature of the lead selenide detector at atarget operating temperature; and a computer system for evaluating theat least one vehicle component based on the image data, wherein theevaluating includes: generating temperature measurement data based onthe image data acquired by the set of imaging devices; and evaluatingthe at least one vehicle component using the temperature measurementdata.

A second aspect of the invention provides a system comprising: animaging component including a set of imaging devices configured toacquire image data based on infrared emissions of at least one vehiclecomponent of a vehicle moving through a field of view of at least one ofthe set of imaging devices, wherein an imaging device in the set ofimaging devices includes a detector and a thermoelectric coolermaintaining an operating temperature of the detector at a targetoperating temperature, and wherein the infrared emissions are within themid-wavelength infrared (MWIR) radiation spectrum.

A third aspect of the invention provides a system comprising: an imagingcomponent including a set of imaging devices configured to acquire imagedata based on infrared emissions of at least one vehicle component of avehicle moving through a field of view of at least one of the set ofimaging devices, wherein an imaging device in the set of imaging devicesincludes a linear array of photoconductor infrared detectors and athermoelectric cooler for maintaining an operating temperature of thelinear array of detectors at a target operating temperature, and whereinthe infrared emissions are within at least one of: the mid-wavelengthinfrared (MWIR) radiation spectrum or the long wavelength infrared(LWIR) radiation spectrum.

Other aspects of the invention provide methods, systems, programproducts, and methods of using and generating each, which include and/orimplement some or all of the actions described herein. The illustrativeaspects of the invention are designed to solve one or more of theproblems herein described and/or one or more other problems notdiscussed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the disclosure will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various aspects of the invention.

FIG. 1 shows an illustrative environment for evaluating a moving vehicleaccording to an embodiment.

FIGS. 2A and 2B show partial configurations of illustrative imagingcomponents according to embodiments.

FIGS. 3A and 3B show partial configurations of illustrative imagingcomponents according to embodiments.

FIG. 4 shows a partial configuration of an illustrative imagingcomponent according to an embodiment.

FIG. 5 shows D* as a function of wavelength for different operatingtemperatures of two types of photoconductive infrared detectors.

FIG. 6 shows spectral radiance emitted by a blackbody at a temperatureof two hundred degrees Fahrenheit.

It is noted that the drawings may not be to scale. The drawings areintended to depict only typical aspects of the invention, and thereforeshould not be considered as limiting the scope of the invention. In thedrawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The inventors recognize a further drawback with the use of commerciallyavailable thermal detectors. In particular, the performance of thermaldetectors, such as thermistor bolometers and pyroelectrics, cannot beimproved by adjusting their operating temperature. In contrast, theperformance of another class of infrared detectors, known asphotodetectors, can be improved by reducing the operating temperature,e.g., using one or more stages of thermoelectric cooling.

As indicated above, aspects of the invention provide an improved systemfor evaluating one or more components of a vehicle. The system includesa set of imaging devices configured to acquire image data based oninfrared emissions of at least one vehicle component of the vehicle asit moves through a field of view of at least one of the set of imagingdevices. An imaging device in the set of imaging devices can include alinear array of photoconductor infrared detectors and a thermoelectriccooler for maintaining an operating temperature of the linear array ofdetectors at a target operating temperature, e.g., below ambient, forimproved sensitivity. The photoconductor infrared detectors can beformed of lead selenide, mercury cadmium telluride, and/or the like,which can provide fast response to enable accurate measurements of thefastest railcar wheels. The infrared emissions can be within at leastone of: the mid-wavelength infrared (MWIR) radiation spectrum or thelong wavelength infrared (LWIR) radiation spectrum. As used herein,unless otherwise noted, the term “set” means one or more (i.e., at leastone) and the phrase “any solution” means any now known or laterdeveloped solution.

Turning to the drawings, FIG. 1 shows an illustrative environment 10 forevaluating a moving vehicle according to an embodiment. To this extent,the environment 10 includes a computer system 20 that can perform aprocess described herein in order to evaluate the vehicle using imagedata acquired as the vehicle moves through a field of view of an imagingcomponent 34. In particular, the computer system 20 is shown includingan evaluation program 30, which makes the computer system 20 operable toevaluate the vehicle by performing a process described herein.

The computer system 20 is shown including a processing component 22(e.g., one or more processors), a storage component 24 (e.g., a storagehierarchy), an input/output (I/O) component 26 (e.g., one or more I/Ointerfaces and/or devices), and a communications pathway 28. In general,the processing component 22 executes program code, such as theevaluation program 30, which is at least partially fixed in storagecomponent 24. While executing program code, the processing component 22can process data, which can result in reading and/or writing transformeddata from/to the storage component 24 and/or the I/O component 26 forfurther processing. The pathway 28 provides a communications linkbetween each of the components in the computer system 20. The I/Ocomponent 26 can comprise one or more human I/O devices, which enable ahuman user 12 to interact with the computer system 20 and/or one or morecommunications devices to enable a system user 12 to communicate withthe computer system 20 using any type of communications link. To thisextent, the evaluation program 30 can manage a set of interfaces (e.g.,graphical user interface(s), application program interface, and/or thelike) that enable human and/or system users 12 to interact with theevaluation program 30. Furthermore, the evaluation program 30 can manage(e.g., store, retrieve, create, manipulate, organize, present, etc.) thedata, such as evaluation data 36, using any solution.

In any event, the computer system 20 can comprise one or more generalpurpose computing articles of manufacture (e.g., computing devices)capable of executing program code, such as the evaluation program 30,installed thereon. As used herein, it is understood that “program code”means any collection of instructions, in any language, code or notation,that cause a computing device having an information processingcapability to perform a particular action either directly or after anycombination of the following: (a) conversion to another language, codeor notation; (b) reproduction in a different material form; and/or (c)decompression. To this extent, the evaluation program 30 can be embodiedas any combination of system software and/or application software.

Furthermore, the evaluation program 30 can be implemented using a set ofmodules 32. In this case, a module 32 can enable the computer system 20to perform a set of tasks used by the evaluation program 30, and can beseparately developed and/or implemented apart from other portions of theevaluation program 30. As used herein, the term “component” means anyconfiguration of hardware, with or without software, which implementsthe functionality described in conjunction therewith using any solution,while the term “module” means program code that enables a computersystem 20 to implement the actions described in conjunction therewithusing any solution. When fixed in a storage component 24 of a computersystem 20 that includes a processing component 22, a module is asubstantial portion of a component that implements the actions.Regardless, it is understood that two or more components, modules,and/or systems may share some/all of their respective hardware and/orsoftware. Furthermore, it is understood that some of the functionalitydiscussed herein may not be implemented or additional functionality maybe included as part of the computer system 20.

When the computer system 20 comprises multiple computing devices, eachcomputing device can have only a portion of the evaluation program 30fixed thereon (e.g., one or more modules 32). However, it is understoodthat the computer system 20 and the evaluation program 30 are onlyrepresentative of various possible equivalent computer systems that mayperform a process described herein. To this extent, in otherembodiments, the functionality provided by the computer system 20 andthe evaluation program 30 can be at least partially implemented by oneor more computing devices that include any combination of general and/orspecific purpose hardware with or without program code. In eachembodiment, the hardware and program code, if included, can be createdusing standard engineering and programming techniques, respectively.

Regardless, when the computer system 20 includes multiple computingdevices, the computing devices can communicate over any type ofcommunications link. Furthermore, while performing a process describedherein, the computer system 20 can communicate with one or more othercomputer systems using any type of communications link. In either case,the communications link can comprise any combination of various types ofoptical fiber, wired, and/or wireless links; comprise any combination ofone or more types of networks; and/or utilize any combination of varioustypes of transmission techniques and protocols.

As discussed herein, the evaluation program 30 enables the computersystem 20 to evaluate vehicle(s) using image data acquired by an imagingcomponent 34. In an embodiment, the image data comprises image dataacquired by a set of infrared imaging devices based on infraredradiation emitted from one or more components of each vehicle. In a moreparticular embodiment, the infrared radiation has a wavelength in themid-wavelength infrared (MWIR) radiation spectrum, e.g., betweenapproximately three and five micrometers (five to eight micrometerinfrared radiation may be blocked by water vapor in the air). Thecomputer system 20 can process the infrared image data to evaluate oneor more components of a vehicle for the presence of one or more defectsusing any solution. Illustrative defects include hot or cold brakes, hotor cold wheels, hot bearings, and/or the like. In response to evaluatingthe presence of a defect, the computer system 20 can initiate any set ofactions, including for example, activating a warning system for anoperator of the vehicle, notifying a station to which the vehicle istraveling, activating a safety system (e.g., slowing the vehicle,removing the vehicle from a road, notifying other vehicles, and/or thelike), identify the vehicle for further inspection, and/or the like.

The imaging component 34 can include one or more of any type ofinfrared-based imaging devices. Furthermore, the imaging component 34can include one or more sub-components related to the imaging device(s).Illustrative sub-components include a set of wheel detectors, a set ofspeedometers, one or more devices for maintaining an atmosphere thatenables effective operation of the imaging device(s) (e.g., shutters,air knives, cooling/heating elements, and/or the like), communicationsdevice(s), and/or the like. In an embodiment, the various components ofthe imaging component 34 communicate with and are controlled by thecomputer system 20. In another embodiment, the imaging component 34includes a set of computing devices capable of controlling the varioussub-components of the imaging component 34 and communicating with thecomputer system 20. In the latter case, the computing device(s) can beconfigured similar to the computer system 20.

In an embodiment, the imaging component 34 includes one or more sets ofinfrared photodetectors, which are capable of acquiring infrared-basedimage data at a target frame rate. For example, a set of infraredphotodetectors can comprise a linear array of photodetectors sensitiveto MWIR radiation. To this extent, an embodiment of the imagingcomponent 34 can include one or more lead selenide (PbSe)-basedphotodetectors. Other possible MWIR photodetectors include lead sulfide(PbS) (e.g., when the vehicles are traveling sufficiently slow), mercurycadmium telluride, known as MCT or HgCdTe, and/or the like.

The target frame rate can be selected based on one or more attributes ofthe vehicle and the corresponding component(s) being imaged. In anembodiment, the vehicle is a rail vehicle, e.g., included in a train,and the component(s) being imaged are the bearings and/or wheels of therail vehicle. In a more particular embodiment, the rail vehicle isincluded in a high speed train, which is capable of traveling at speedsof up to approximately four hundred fifty kilometers per hour. Inanother embodiment, the vehicle is a wheeled vehicle, such as a truck,and the component(s) being imaged are the brake rotors or brake drums(e.g., imaged through approximately two inch diameter openings in awheel) and/or wheels of the truck. In a more particular embodiment, thevehicle is traveling at highway speeds, e.g., at speeds up toapproximately one hundred twenty kilometers per hour. In either case, atarget frame rate for evaluating the component(s) of the vehicle can beapproximately two thousand frames per second.

In any event, the imaging device(s) included in the imaging component 34can be permanently or temporarily placed adjacent to a path of travelfor the vehicle(s) being imaged. The placement can be such that thedesired component(s) of the vehicle will pass through the field of viewof one or more of the imaging devices as the vehicle travels in anormal/expected path past the imaging device(s). The imaging component34 can be configured to detect a presence of the vehicle and operate theimaging device(s) to acquire image data having a sufficient resolutionto evaluate the component(s). In an embodiment, the resolution isapproximately one quarter inch in the vertical and horizontaldirections.

FIGS. 2A and 2B show partial configurations of illustrative imagingcomponents 234A, 234B, respectively, according to embodiments. In FIG.2A, an infrared imaging device 240 is mounted adjacent to a set of rails2A, on which rail wheels 3A of a rail vehicle (not shown for clarity)travel. In FIG. 2B, an infrared imaging device 240 is mounted adjacentto a road 2B (e.g., a highway), on which the wheels 3B of a vehicle (notshown for clarity) travel. In an embodiment, the imaging component 234Bis configured to evaluate the wheels 3B of trucks and other largevehicles traveling along a given road 2B.

As the wheel 3A, 3B travels, e.g., in a direction A, the wheel 3A, 3Bcan be detected by a wheel detector 242 included in the imagingcomponent 234A, 234B. The wheel detector 242 can be any type of devicecapable of reliably detecting the presence of the corresponding type ofwheel 3A, 3B. Additionally, the wheel detector 242 can be configured todetermine one or more attributes of the wheel 3A, 3B, such as a speed atwhich the wheel 3A, 3B is traveling. In response to detecting a wheel3A, 3B, the wheel detector 242 can send a signal, e.g., to the computersystem 20 (FIG. 1) and/or the imaging device 240, which causes operationof the infrared imaging device 240 and/or one or more components relatedthereto to be initialized.

To this extent, the wheel detector 242 can be placed such that detectionof the wheel 3A, 3B provides sufficient time to enable the infraredimaging device 240, and/or the component(s) related thereto, to beinitialized for operation. Such a placement can be readily determinedbased on a maximum speed for the wheels 3A, 3B and an initializationtime for the infrared imaging device 240 and/or the component(s) relatedthereto. Furthermore, it is understood that an imaging component 234A,234B can include multiple wheel detectors 242, each of which can detecta wheel 3A, 3B as it passes a unique location to enable, for example,calculation of a speed of the wheel 3A, 3B (when the detectors areplaced a known distance apart), detection of wheels 3A, 3B approachingfrom opposite sides of the infrared imaging device 240 (e.g., to handlevehicles traveling in different directions), detection of a wheel 3A, 3Bimmediately adjacent to a field of view of the infrared imaging device240, and/or the like.

As shown in FIG. 2A, the rail wheel 3A includes a hub 4 and a rim 5. Ingeneral, the rail wheel 3A can have a diameter between approximatelytwenty-eight and forty-four inches, and the wheel hub 4 can beapproximately fourteen to twenty-two inches above the rail 2A. Asillustrated, the infrared imaging device 240 can be configured such thatboth the hub 4 and the rim 5 of the rail wheel 3A will pass through thevertical field of view 244 of the infrared imaging device 240 as therail wheel 3A travels along the rail 2A.

As shown in FIG. 2B, the wheel 3B includes a hub 7 and a tire 8.Furthermore, the wheel 3B includes a plurality of openings 9. Each ofthe openings 9 can have a diameter of approximately two inches, throughwhich a portion of a brake rotor of the corresponding vehicle isvisible. However, it is understood that the configuration of theopenings 9 on wheel 3B is only illustrative of various possible wheelopening configurations for a road vehicle. A typical truck wheel 3B canhave a diameter between approximately forty and forty-four inches. Asillustrated, the infrared imaging device 240 can be configured such thatthe hub 7, the tire 8, and one or more of the openings 9 of the wheel 3Bwill pass through the vertical field of view 244 of the infrared imagingdevice 240 as the wheel 3B travels along the road 2B.

In each imaging component 234A, 234B, the infrared imaging device 240 isshown mounted on an upright support 250. The support 250 can compriseany type of support, which is permanently or temporarily locatedadjacent to the rail 2A (FIG. 2A) or the edge of the road 2B (FIG. 2B).In either case, the support 250 can provide sufficient stability duringthe passing of a vehicle to enable the infrared imaging device 240 tocapture infrared data having sufficient clarity and resolution forevaluating the wheel 3A, 3B and/or other components of the vehicle. Inan embodiment, the infrared imaging device 240 is mounted pointingslightly down, e.g., at a downward angle of approximately five degrees,to provide protection from rain, snow, debris buildup, and/or the like.

The upright support 250 can be located a predetermined distance from therail 2A (FIG. 2A) or the edge of the road 2B (FIG. 2B). The infraredimaging device 240 can include a lens system 246, which provides thedesired vertical field of view 244. The predetermined distance andheight at which the infrared imaging device 240 is mounted, can beselected based on the vertical field of view 244 and the correspondingdimensions of the wheel 3A, 3B using any solution. In an embodiment, thepredetermined distance is approximately four feet, the height isapproximately eighteen inches above the surface on which the wheel 3A,3B travels (e.g., the rail 2A or the road 2B), and the vertical field ofview 244 is approximately thirty degrees. When implemented on the sideof a road 2B, it is understood that the distance between the wheel 3Band the infrared imaging device 240 can vary, e.g., by approximately +/−two feet.

In an embodiment, the infrared imaging device 240 comprises a lineararray of photoconductor infrared detectors for acquiring MWIR imagedata. A photoconductor infrared detector is a class of photodetectorsthat undergo a large resistance change on illumination with radiation.Another class of photodetectors is photovoltaic, which generate avoltage in response to illumination. In a more particular embodiment,the photoconductor infrared detectors are formed of lead selenide(PbSe). In an illustrative embodiment, the linear array can comprise asixty-four by one linear array of photoconductive infrared detectors.Regardless, a horizontal field angle for the linear array can beapproximately 0.2 to 0.3 degrees, which can be selected based upon thelens system 246 and a desired array pixel size (e.g., approximately onequarter inch squares in an embodiment). However, it is understood thatthe linear array size and pixel size are only illustrative. To thisextent, various other linear array sizes (e.g., 256×1 or greater) and/orpixel sizes can be utilized.

As a wheel 3A, 3B passes through the field of view 244 of the imagingdevice 240, the imaging device can acquire multiple frames of image datacorresponding to MWIR radiation emitted by the imaged components of thewheel 3A, 3B and/or corresponding vehicle. When the infrared imagingdevice 240 comprises a linear array, each frame corresponds to avertical slice of the wheel 3A, 3B. As described herein, operation ofthe infrared imaging device 240 can be synchronized with the passage ofa wheel 3A, 3B using, for example, data provided by the wheel detector242.

The imaging device 240 can provide the acquired infrared image data, ordata corresponding thereto, for processing by the computer system 20(FIG. 1) using any solution. When the imaging device 240 comprises alinear array, each frame will represent a different portion (e.g.,slice) of the wheel 3A, 3B due to the motion of the wheel 3A, 3B betweenthe capture of each frame. The computer system 20 can assemble a seriesof frames into a two-dimensional image of the wheel 3A, 3B. Each lineportion of the resulting two-dimensional image is temporally shiftedbased upon the frame rate of the imaging device 240. The computer system20 can store the infrared image data, the two-dimensional image, and/orthe like, as evaluation data 36 corresponding to the wheel 3A, 3B.

The computer system 20 can process the infrared image data to evaluateone or more attributes of the wheel 3A, 3B and/or another component ofthe vehicle related to the wheel. For example, the computer system 20can process each frame/two-dimensional image to determine acorresponding temperature distribution of the imaged wheel 3A, 3B and/orother components of the vehicle present in the image data. Thetemperatures calculated by the computer system 20 based on MWIR-basedimage data should not be influenced by variations in the distancebetween the wheel (particularly the wheel 3B) and the infrared imagingdevice 240. As a result, it is not critical to know an exact distancebetween the infrared imaging device 240 and the wheel 3A, 3B. Thetwo-dimensional image of the wheel 3A, 3B generated by the computersystem 20 can be elliptical. The size and shape of the wheel 3A, 3B inthe image can depend on the distance between the infrared imaging device240 and the wheel 3A, 3B, the frame rate of the infrared imaging device240, the speed of the wheel 3A, 3B, and/or the like. In an embodiment,the computer system 20 can implement one or more feature extractionalgorithms to calculate a distance to the wheel 3A, 3B, if desired, tocalculate a speed of the wheel 3A, 3B from the elliptical shape, and/orthe like.

Regardless, when a rail wheel 3A is imaged, the computer system 20 canprocess the infrared image data to obtain temperature measurement datacorresponding to the hub 4, the rim 5, and/or the like, using anysolution. The computer system 20 can use the temperature measurementdata for the rail wheel 3A to evaluate a condition of wheel bearings,brakes, the wheel 3A, and/or the like, using any solution. When a roadwheel 3B is imaged, the computer system 20 can process the infraredimage data to obtain temperature measurement data corresponding to thehub 7, tire 8, a portion of a brake rotor (e.g., visible through theopenings 9), and/or the like, using any solution. The computer system 20can use the temperature measurement data for the road wheel 3B toevaluate a condition of wheel bearings, brakes, tires, and/or the like,using any solution. For example, the computer system 20 can compare thetemperature measurement data to determine whether the temperatures arewithin an expected range of temperatures (e.g., relative to a runningaverage), exceed or are below a maximum/minimum allowable temperature,are correlated with the temperature measurements acquired for othercomponents (e.g., other wheels of the same vehicle, other rail cars onthe same train, and/or the like), and/or the like.

It is understood that various alternative configurations of the imagingcomponents 234A, 234B are possible. For example, more or less of eachwheel 3A, 3B can be imaged, multiple infrared imaging devices 240 can beincluded, other components of the vehicle can be imaged, and/or thelike. Similarly, it is understood that each imaging component 234A, 234Bcan include a similarly configured infrared imaging device 240 on anopposing side of the rail(s) 3A or road 3B to image wheels 3A, 3B on theopposing side of the vehicle.

FIGS. 3A and 3B show partial configurations of illustrative imagingcomponents 334A, 334B according to embodiments. Similar to the imagingcomponents 234A, 234B shown in FIGS. 2A and 2B, the imaging components334A, 334B include a set of infrared imaging devices 340A, 340B, whichare mounted on an upright support 350 located adjacent to a set of rails2A and a road 2B, respectively. Additionally, the imaging components334A, 334B are shown including a wheel detector 342, which can detect apassing wheel 3A, 3B, and initiate operation of the infrared imagingdevices 340A, 340B, synchronize operation of the imaging devices 340A,340B with the wheel 3A, 3B moving in the direction A, and/or the like,as described herein.

In these embodiments, the imaging components 334A, 334B include twoinfrared imaging devices 340A, 340B. Each infrared imaging device 340A,340B can be configured similarly to the infrared imaging device 240described in conjunction with FIGS. 2A and 2B. For example, eachinfrared imaging device 340A, 340B can comprise a linear array ofphotoconductor infrared detectors for acquiring MWIR image data.However, each infrared imaging device 340A, 340B can have a narrowervertical field of view 344A, 344B, respectively, than that of theinfrared imaging device 240. To this extent, in order to obtain the sameresolution as the infrared imaging device 240, the linear array for eachinfrared imaging device 340A, 340B can be smaller than the linear arrayof the infrared imaging device 240. The use of multiple smaller linearphotoconductive arrays for concurrent imaging of different sections ofinterest of the wheel 3A, 3B can provide a solution having: a lower cost(e.g., a photoconductive array can be expensive as the number ofelements are increased); a more detailed and higher resolution imagedata for wheel 3A, 3B sections of interest (e.g., hot bearings and hotrims); less image data to process; and/or the like.

Each infrared imaging device 340A, 340B can be separately configuredbased on a target area to be imaged. For example, the infrared imagingdevice 340A can have a field of view that is at least two times largerthan the field of view of the infrared imaging device 340B. Similarly,the infrared imaging device 340A can comprise a linear array ofphotoconductor infrared detectors that is at least two times larger thanthe linear array of photoconductor infrared detectors for the infraredimaging device 340B. In an embodiment, the infrared imaging device 340Acomprises a thirty-two by one linear array of photoconductor infrareddetectors formed of PbSe. A corresponding lens system 346A can provide avertical field of view of approximately seventeen degrees. The infraredimaging device 340A can be mounted approximately eighteen (in FIG. 3A)or twenty (in FIG. 3B) inches above the surface on which the wheel 3A,3B is traveling pointing slightly down. In this configuration, theinfrared imaging device 340A can acquire infrared image datacorresponding to the hub 4, 7 of the wheel 3A, 3B, respectively, whichcan enable detection of a hot bearing.

In an embodiment, the infrared imaging device 340B comprises an eight byone linear array of photoconductor infrared detectors formed of PbSe. Acorresponding lens system 346B can provide a vertical field of view ofapproximately 3.6 degrees. The infrared imaging device 340B can bemounted approximately three inches above the surface on which the wheel3A, 3B is traveling pointing slightly down. In this configuration, theinfrared imaging device 340B can acquire infrared image datacorresponding to the rim 5 of the wheel 3A, or the rim (which caninclude one or more of the openings 9) and/or the tire 8 of the wheel3B, respectively, which can enable detection of a hot rim, a hot tire,hot brakes, and/or the like.

In some applications, such as transit rail service, the wheel hub 4, 7,may be covered by other hardware, and therefore not viewable orimageable from the side of the rail/road. In this case, one or moreinfrared imaging devices can be mounted in an alternative location,which enables the capture of infrared image data for the wheel hub 4, 7.For example, FIG. 4 shows a partial configuration of an illustrativeimaging component 434 according to an embodiment. In this case, aninfrared imaging device 440 and corresponding lens system 446 is mountedin a housing 452 connected to the rail 2A and located below a topsurface of the rail 2A. The infrared imaging device 440 is shown havinga field of view 444 which is substantially vertical and enablesacquiring infrared image data for a bearing 11 of a wheel 3A. However,it is understood that this is only illustrative of various possibleconfigurations. For example, in an embodiment, the infrared imagingdevice 440 can be configured to acquire infrared image data for a rim 5of the wheel 3A.

The housing 452 can be mounted to the rail 2A using any solution. Thehousing 452 can include a movable shutter 454, which covers an openingwhen the infrared imaging device 440 is not in use to protect theinterior from rain, snow, ice, and/or the like. The movable shutter 454can be moved away from the opening when the infrared imaging device 440is in use, e.g., in response to a wheel being detected by a wheeldetector. Additionally, the housing 452 can include one or morecomponents, such as rotating mirrors, air knives, and/or the like, toprotect the infrared imaging device 440 and lens system 446 from blowingdirt and other contaminants while the movable shutter 454 is open.

The infrared imaging device 440 can be configured similar to theinfrared imaging devices described herein. In an embodiment, theinfrared imaging device 440 comprises a single photoconductor infrareddetector or a linear array of photoconductor infrared detectors whichcan be formed of, for example, PbSe. Use of photoconductor infrareddetector(s) in this case, where the infrared imaging device 440 issubjected to vibrations induced by a passing train, eliminates themicrophonic noise, which causes false alarms with pyroelectric detectorstypically used in the prior art.

The use of a linear array of photoconductor infrared detectors describedherein enables high speed capture (approximately two thousand frames persecond) of the radiant energy emitted by various components beingimaged. Such a high speed capture can be required to perform certainanalysis of one or more components of a vehicle traveling at a normaloperating speed. For example, as described herein, for a roadsideembodiment, the road vehicle (e.g., a truck) can be traveling at ahighway speed (e.g., approximately seventy miles per hour or faster). Inthis case, in order to analyze the radiant energy emitted by the brakerotor, which is imaged through the openings 9 (FIGS. 2B and 3B), a framerate of approximately two thousand frames per second may be necessary.Similarly, for a rail vehicle traveling at high speeds (e.g., up toapproximately four hundred fifty kilometers per hour), a frame rate ofapproximately two thousand frames per second may be necessary to analyzethe hub 4 and/or rim 5 of each rail wheel 3A. Since the features ofinterest on the rail wheel 3A are continuous (e.g., are fully visible),the rail vehicle can be traveling at a much higher speed than the roadvehicle.

As described herein, an infrared imaging device can include one or morephotoconductor infrared detectors made of lead selenide. Photoconductivelead selenide has a relatively fast response, e.g., a typical rise timeof approximately ten microseconds, and is sensitive to MWIR radiationhaving wavelengths between approximately 1.5 and 5.2 micrometers.

A commonly used and appropriate figure of merit for infrared detectorsis D*, where D* is measured in cmHz^(1/2) Watt⁻¹. D* is a measure of thesignal to noise provided by an infrared detector after normalizing forthe detector element area and the measurement bandwidth, therebyenabling different detectors to be compared equitably. A value of D* ina range of 1E+10 cmHz^(1/2) Watt⁻¹ and higher can provide meaningfulmeasurement of radiant energy for many applications, enabling surfacetemperatures and small temperature differences of radiating surfaces tobe resolved via infrared measurements. Lead selenide-based detectorsprovide a D* in the range of 1E+10 cmHz^(1/2) Watt⁻¹ at ambienttemperature (25° C.) operation. Performance of a lead selenide-baseddetector (and detector arrays) can be improved by operating thedetector(s) at lower temperatures. Such an improvement may be requiredfor MWIR measurements for objects at or near ambient temperatures, e.g.,due to a relatively small amount of MWIR energy emitted by such objects.

FIG. 5 shows D* as a function of wavelength for different operatingtemperatures of two types of photoconductive infrared detectors. Inparticular, the D* for lead selenide (PbSe) and lead sulfide (PbS)detectors are shown for operating temperatures of −45, −25, 0, and 23degrees Celsius. An improvement in D* by a factor of two to three can beobtained by operating the detector or detector array at reducedtemperatures, e.g., 0° C. or below. While the PbS detectors have ahigher D* than the PbSe detectors, these detectors are much slower,e.g., with rise times in the hundreds of microseconds. As a result, useof a PbS detector can be limited to applications in which lower framerates are acceptable (e.g., slower speeds of the vehicles). A mercurycadmium telluride (MCT)-based detector can have sufficient sensitivity(D*) and operate sufficiently fast to provide high speed imaging. Thesedetectors can be operated in either a photovoltaic or a photoconductivemode. Use of an MCT-based detector can include maintaining a targetoperating temperature using a cryogenic cooling solution, e.g., anoperating temperature of approximately 77 degrees Kelvin maintainedusing a liquid nitrogen cooling solution, or the like.

FIG. 6 shows spectral radiance emitted by a blackbody at a temperatureof two hundred degrees Fahrenheit. Calculations show that less than fivepercent of the energy is emitted in the infrared region between one tofive micrometers wavelength. As illustrated, most of the energy radiatedby such warm (as opposed to hot) objects is in the long wavelengthinfrared (LWIR) region. To this extent, it is desirable to have arelatively high signal to noise ratio for an MWIR imaging device inorder to accurately measure warm (e.g., a temperature less thanapproximately two hundred degrees F.) wheel/vehicle components.

In an embodiment, an infrared imaging device described herein maintainsan operating environment, which enables the detector element(s) toacquire data having a signal to noise ratio sufficient for a givenapplication. In a more specific embodiment, the infrared imaging devicecan maintain the detector element(s) at a target operating temperature,which can be below ambient. For example, the infrared imaging device caninclude thermoelectric coolers, which are mounted inside the detectorpackage to reduce the operating temperature of the infrared detector(s).In an embodiment, the thermoelectric cooler is a single stagethermoelectric cooler, which is capable of reducing the operatingtemperature to approximately −25° C. for ambient temperatures of 25° C.with a power consumption of 1 to 2 Watts. A lower operating temperaturecan be achieved using two or three stage thermoelectric coolers, whichhave a proportionally higher power consumption. In an embodiment, aninfrared imaging device comprises a self-contained device capable ofmaintaining a target operating temperature. In another embodiment, thecomputer system 20 (FIG. 1) is configured to operate a set ofthermoelectric coolers to maintain the target operating temperature. Ineither case, the target operating temperature can be preciselycontrolled, e.g., within +/−0.01° C. of the target operatingtemperature.

A linear array of PbSe-based detector elements with operatingtemperatures of, for example, −4° C., is currently available. A secondstage of cooling can be added between the cooled array and an externalheat radiator to further reduce the temperature. A signal to noiseimprovement of approximately 3%/° C. is estimated for furthertemperature reduction, e.g., down to approximately −80° C. While use ofcooling elements is described herein, it is understood that an infraredimaging device can include one or more heating elements, which can beutilized to maintain the target operating temperature depending on theoperating environment and/or the target operating temperature. In anembodiment, the set of thermoelectric coolers is operated using areverse current to provide heating. In another embodiment, an infraredimaging device described herein can include an additional heatingelement, such as a resistive heater, which can be utilized, for example,in operating environments with temperatures below −55° C.

In addition to improvements in sensitivity, the stabilization of thedetector temperature results in reduced noise and drift. Hence,temperature stabilization via use of thermoelectric coolers can bebeneficial even if temperature reduction is not required for sensitivityenhancement. Furthermore, as illustrated in FIG. 5, the wavelengthresponse of a PbSe or PbS detector shifts to longer wavelengths at thereduced operating temperatures. To this extent, cooling of a detectordescribed herein can provide an additional improvement in performancefor measurements conducted on warm objects. In particular, as shown inFIGS. 5 and 6, significantly more infrared energy will detected fromobjects at 200° F. as the detector response shifts to longer wavelengthswith cooling below 23° C. The steep increase in spectral radianceemitted by warm objects in the wavelength region around five microns(FIG. 6) overlaps with the increase in the long wavelength detectionedge (FIG. 5) of the cooled PbSe detectors.

While shown and described herein as a method and system for evaluatingone or more components of a vehicle, it is understood that aspects ofthe invention further provide various alternative embodiments. Forexample, in one embodiment, the invention provides a computer programfixed in at least one computer-readable medium, which when executed,enables a computer system to evaluate component(s) of the vehicle. Tothis extent, the computer-readable medium includes program code, such asthe evaluation program 30 (FIG. 1), which enables a computer system toimplement some or all of a process described herein. It is understoodthat the term “computer-readable medium” comprises one or more of anytype of tangible medium of expression, now known or later developed,from which a copy of the program code can be perceived, reproduced, orotherwise communicated by a computing device. For example, thecomputer-readable medium can comprise: one or more portable storagearticles of manufacture; one or more memory/storage components of acomputing device; paper; and/or the like.

In another embodiment, the invention provides a method of providing acopy of program code, such as the evaluation program 30 (FIG. 1), whichenables a computer system to implement some or all of a processdescribed herein. In this case, a computer system can process a copy ofthe program code to generate and transmit, for reception at a second,distinct location, a set of data signals that has one or more of itscharacteristics set and/or changed in such a manner as to encode a copyof the program code in the set of data signals. Similarly, an embodimentof the invention provides a method of acquiring a copy of the programcode, which includes a computer system receiving the set of data signalsdescribed herein, and translating the set of data signals into a copy ofthe computer program fixed in at least one computer-readable medium. Ineither case, the set of data signals can be transmitted/received usingany type of communications link.

In still another embodiment, the invention provides a method ofgenerating a system for evaluating component(s) of a vehicle. In thiscase, the generating can include configuring a computer system, such asthe computer system 20 (FIG. 1), to implement the method of evaluatingcomponent(s) of the vehicle. The configuring can include obtaining(e.g., creating, maintaining, purchasing, modifying, using, makingavailable, etc.) one or more hardware components, with or without one ormore software modules, and setting up the components and/or modules toimplement a process described herein. To this extent, the configuringcan include deploying one or more components to the computer system,which can comprise one or more of: (1) installing program code on acomputing device; (2) adding one or more computing and/or I/O devices tothe computer system; (3) incorporating and/or modifying the computersystem to enable it to perform a process described herein; and/or thelike.

The foregoing description of various aspects of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and obviously, many modifications and variations arepossible. Such modifications and variations that may be apparent to anindividual in the art are included within the scope of the invention asdefined by the accompanying claims.

What is claimed is:
 1. A system comprising: an imaging device configuredto acquire infrared-based image data corresponding to at least onevehicle component of a vehicle moving through a field of view of theimaging device, wherein the imaging device includes an infrared detectorand a temperature element for maintaining an operating temperature ofthe infrared detector at a target operating temperature, wherein thetemperature element comprises a multi-stage cooler configured tomaintain the target operating temperature between approximately −80degrees Celsius and approximately −25 degrees Celsius, and wherein theinfrared-based image data is at least partially based on infrared withinthe mid-wavelength infrared (MWIR) radiation spectrum; and a computersystem for evaluating the at least one vehicle component based on theinfrared-based image data, wherein the evaluating includes: generatingtemperature distribution data for the at least one vehicle componentbased on the infrared-based image data acquired by the imaging device;and evaluating the at least one vehicle component using the temperaturedistribution data.
 2. The system of claim 1, wherein the infrareddetector is a lead selenide detector, and wherein the imaging device iscapable of acquiring infrared image data at a rate of at leastapproximately two thousand frames per second.
 3. The system of claim 1,further comprising a second imaging device, wherein one of the imagingdevice or the second imaging device is configured to acquireinfrared-based image data including a central region of a wheel of themoving vehicle, and the other of the imaging device or the secondimaging device is configured to acquire infrared-based image dataincluding an outer region of the wheel of the moving vehicle, whereinthe imaging device and the second imaging device acquire infrared-basedimage data for distinct regions of the wheel.
 4. The system of claim 3,wherein the image data including the central region of the wheelincludes at least two times a number of infrared pixels as the imagedata including the outer region of the wheel.
 5. The system of claim 1,wherein the imaging device is located adjacent to a rail on which thevehicle is moving.
 6. The system of claim 1, wherein the imaging deviceis located adjacent to a road on which the vehicle is moving, andwherein the vehicle can be moving up to at least approximately seventymiles per hour while the imaging device acquires the image data.
 7. Thesystem of claim 1, further comprising a second imaging device includinga second infrared detector configured to generate infrared-based imagedata at least partially based on infrared, and wherein the infrared arefurther within the long wavelength infrared (LWIR) radiation spectrum.8. A system for evaluating a vehicle moving at any speed in a range ofspeeds including a maximum main line operating speed of the vehicle, thesystem comprising: an imaging device configured to acquireinfrared-based image data corresponding to at least one vehiclecomponent of the vehicle moving through a field of view of the imagingdevice, wherein the imaging device includes a high speed lead selenideinfrared detector and a temperature element maintaining an operatingtemperature of the high speed infrared detector at a target operatingtemperature, wherein the target operating temperature for the leadselenide infrared detector is between approximately −80 degrees Celsiusand approximately −25 degrees Celsius, and wherein the infrared-basedimage data is at least partially based on infrared within themid-wavelength infrared (MWIR) radiation spectrum; and means forevaluating the at least one vehicle component using the infrared-basedimage data.
 9. The system of claim 8, wherein the imaging device iscapable of acquiring infrared image data at a rate of at leastapproximately two thousand frames per second.
 10. The system of claim 8,wherein the temperature element comprises a multi-stage coolerconfigured to precisely control the operating temperature.
 11. Thesystem of claim 8, wherein the means for evaluating includes a computersystem for evaluating the at least one vehicle component based on theimage data, wherein the evaluating includes: generating temperaturemeasurement data based on the image data acquired by the imaging device;and evaluating the at least one vehicle component using the temperaturemeasurement data.
 12. The system of claim 8, wherein the imaging devicecomprises a linear array of photoconductor infrared detectors configuredto acquire image data corresponding to only a central region of a wheelof the moving vehicle.
 13. The system of claim 12, further comprising asecond imaging device, wherein the second imaging device is configuredto acquire image data corresponding to only an outer region of the wheelof the moving vehicle, wherein the second imaging device comprises alinear array of photoconductor infrared detectors.
 14. A system forevaluating a vehicle moving at any speed in a range of speeds includinga maximum main line operating speed of the vehicle, the systemcomprising: a plurality of imaging devices configured to acquireinfrared-based image data corresponding to distinct regions of thevehicle, wherein the plurality of imaging devices includes at least twoimaging devices including: a high speed linear array of photoconductorinfrared detectors; and a temperature element for maintaining anoperating temperature of the linear array of photoconductor infrareddetectors at a target operating temperature between approximately −80degrees Celsius and approximately −25 degrees Celsius, and wherein theinfrared-based image data is at least partially based on infrared withinat least one of: the mid-wavelength infrared (MWIR) radiation spectrumor the long wavelength infrared (LWIR) radiation spectrum; and means forevaluating the at least one vehicle component using the infrared-basedimage data.
 15. The system of claim 14, wherein the temperature elementof at least one of the at least two imaging devices comprises amulti-stage cooler configured to precisely control the target operatingtemperature.
 16. The system of claim 14, wherein the distinct regions ofthe vehicle correspond to distinct regions of a component of thevehicle, and wherein a size of the linear array of photoconductorinfrared detectors for each of the at least two imaging devices differby a factor of at least two.
 17. The system of claim 14, wherein thevehicle is one of: a road vehicle traveling up to at least approximatelyseventy miles per hour or a rail vehicle traveling up to at leastapproximately four hundred fifty kilometers per hour.
 18. The system ofclaim 14, further comprising a computer system for evaluating the atleast one vehicle component based on the image data, wherein theevaluating includes: generating temperature measurement data based onthe image data acquired by the plurality of imaging devices; andevaluating the at least one vehicle component using the temperaturemeasurement data.
 19. The system of claim 14, wherein the evaluatingdetermines a presence of at least one overheating component.
 20. Thesystem of claim 14, wherein the high speed linear array ofphotoconductor infrared detectors includes at least one of: leadselenide photoconductor infrared detectors or mercury cadmium telluridephotoconductor infrared detectors.